The present invention relates generally to a method and system for computer aided design (CAD) of electrical conductors routed on planar surfaces and in particular to routing electrical conductors with slits.
Flat panel displays (FPD) may include two glass plates that are glued together but separated by a narrow gap. Seals are used to glue the glass plates and contain the liquid crystal material used with the FPD. During FPD manufacture, adhesive is applied to the seals and cured by ultra-violet (UV) light. Thin films of conductors, hereinafter also referred to as “wires”, serving to carry electrical signals may be manufactured on the glass plates but may block some of the UV light needed to cure the adhesive adjoining the conductors. Narrow stripes, hereinafter also referred to as “slits”, represent conductor that is removed wherever conductor traces overlap seal regions so that the UV light may go through the slits and cure the adhesive during manufacture. It is understood that removing narrow stripes of conductor from a wire is the same as adding slits to the wire.
Computer aided design (CAD) tools called routers are used to automatically generate digital patterns corresponding to wire routes on planar surfaces. One such CAD technique is described in U.S. Pat. No. 7,779,379, entitled “Template-Based Gateway Model Routing System”, which describes an automated way to route wires within a corridor region according to a routing template. The routing template includes saved data that is associated with user specified constraints such as the shape and location of the corridor region, and wire routing constraints such as the locations of wire terminal edges, the width, spacing, alignment, resistance, and other attributes of the conductors. However, existing CAD routers do not automatically handle slit placement. Therefore designers initially ignore slits, run the CAD router, and then add slits manually. If there is no routing constraint involving resistance values of the wire, the manual addition of slits may be acceptable. However, because slits change the resistance of a wire compared to the same wire without slits, the design goals may be compromised. Then, the designer may need to calculate the resistance value for the wires with slits. Often, the resistance value with slits is unacceptably high and the designer then needs to adjust wire widths, re-do slit placement, and re-calculate the wire resistances, which takes a long time. Therefore, a CAD routing tool that automatically routes wires and places slits to meet design constraints would be desired to reduce design time.